685997 has 4 divisors (see below), whose sum is σ = 738780. Its totient is φ = 633216.

The previous prime is 685991. The next prime is 686003. The reversal of 685997 is 799586.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 799586 = 2 ⋅399793.

It is an interprime number because it is at equal distance from previous prime (685991) and next prime (686003).

It can be written as a sum of positive squares in 2 ways, for example, as 139876 + 546121 = 374^2 + 739^2 .

It is a cyclic number.

It is not a de Polignac number, because 685997 - 2¹⁰ = 684973 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (685991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26372 + ... + 26397.

It is an arithmetic number, because the mean of its divisors is an integer number (184695).

2⁶⁸⁵⁹⁹⁷ is an apocalyptic number.

It is an amenable number.

685997 is a deficient number, since it is larger than the sum of its proper divisors (52783).

685997 is a wasteful number, since it uses less digits than its factorization.

685997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52782.

The product of its digits is 136080, while the sum is 44.

The square root of 685997 is about 828.2493585871. The cubic root of 685997 is about 88.1943449291.

The spelling of 685997 in words is "six hundred eighty-five thousand, nine hundred ninety-seven".